1. Field of the Invention
The present invention relates to a network linkage type private branch exchange (Private Branch Exchange, hereinafter referred to as a “PBX”) system provided in an order reception center of a mail-order firm and the like, and more particularly, to a network linkage type PBX system enabling information to be exchanged among computers connected to a plurality of PBXS, a control method thereof and a recording medium recording a control program therefor.
2. Description of the Related Art
A network linkage type PBX system is a computer network where voice data is transmitted and received among terminal devices (e.g. telephone) connected to a plurality of PBXs through a switched line using a telephone network, while information is exchanged between computers connected to each PBX through other dedicated line than the switched line. Use of this computer network enables computers disposed in a plurality of places of business to divisionally possess programs and data and use the same among them or when a certain computer needs processing exceeding its own capacity, allows the computer to ask other computer in the network to conduct the processing and return the processing results thereafter.
A network linkage type PBX system of this kind has, for example, as illustrated in FIG. 6, bases 10, 20 and 30 such as an order reception center of a mail-order firm. The base 10 includes a PBX11, a telephone network interface (e.g. trunk) 12, a terminal device (e.g. extension) 13, a computer (server) 14, and a data base (DB) 15. The base 20 includes, a PBX21, a trunk 22, an extension 23, a computer (server) 24, a data base (DB) 25, and computer terminals (clients) 26 and 27. The base 30 includes a PBX31, a trunk 32, an extension 33, a computer (server) 34 and a data base (DB) 35. Connected to the PBX11 through a switched line L1 using a telephone network is the PBX21 to which the PBX31 is connected through a switched line L2. To the computer (server) 14, the computer terminal (client) 26 is connected through a dedicated line L3. To the computer (server) 34, the computer terminal (client) 27 is connected through a dedicated line L4. These dedicated lines L3 and L4 are formed, for example, by a WAN (Wide Area Network).
The trunks 12, 22 and 32 relay data between the telephone network and the PBXs 11, 21 and 31, respectively. The extensions 13, 23 and 33 transmit the data between the PBXs 11, 21, 31 and an operator, respectively. The computers (servers) 14, 24, and 34 are connected to the PBXs 11, 21 and 31, respectively, to conduct predetermined processing based on the data. In the data bases (DB) 15, 25 and 35, data necessary for the processing at the computers (servers) 14, 24 and 34 is stored. The computer terminals (clients) 26 and 27 are provided for subsidiary work for the computer (server) 24.
FIG. 7 is a diagram schematically showing one example of a structure of the PBX11 in FIG. 6.
The PBX11 includes a channel switch 11a, a channel switch control unit 11b, a call control core unit 11c, a communication control unit lid, a central processing unit (hereinafter, referred to as “CPU”) 11e and a memory (e.g. ROM) 11f. The channel switch 11a establishes a connection between the trunk 12 and the extension 13. The channel switch control unit 11b gives an instruction on operation to the channel switch 11a. The call control core unit 11c controls switching operation of the PBX11. The communication control unit 11d sends data based on a low layer protocol such as TCP/IP. The CPU 11e controls the entire PBX11. In the ROM 11f, a control program for operating the CPU 11e is recorded. The PBXs 21 and 31 have the same structure as that of the PBX11.
FIG. 8 is a flow chart for use in explaining operation of the network linkage type PBX system shown in FIG. 6.
With reference to the figure, description will be made of operation conducted when the network linkage type PBX system of FIG. 6 is disposed in an order reception center of a mail-order firm.
Customer dials a telephone number of the base 10 by a telephone in order to order a commodity. Then, the call arrives at the PBX11 through the trunk 12 from the telephone network and the PBX11 is connected to the extension 13 by the control of the CPU11e in the PBX11, so that an operator of the extension 13 conducts work for accepting an order. Also at the bases 20 and 30, the same order reception work is conducted. Then, operation record data D11, D21 and D31 of a series of order reception work is output from the PBXs 11, 21 and 31, summed up at the computers (servers) 14, 24 and 34 and stored in the data bases (DB) 15, 25 and 35, respectively.
When a failure occurs in the computer (server) 14 here, for example, an operator of the computer (server) 24 moves from the front of the computer (server) 24 to the front of the computer terminal (client) 26 as shown in FIG. 8 (Step 801). The operator operates the computer terminal (client) 26 to connect the computer terminal (client) 26 to the computer (server) 14 through the dedicated line L3 (Step 802). The contents of the data base (DB) 15 connected to the computer (server) 14 are copied (uploaded) on the side of the computer terminal (client) 26 and sent out to a printer not shown or the like (Step 803).
Similarly, when a failure occurs in the computer (server) 34, the operator moves from the front of the computer (server) 34 to the front of the computer terminal (client) 27. The operator operates the computer terminal (client) 27 to connect the computer terminal (client) 27 to the computer (server) 34 through the dedicated line L4. The contents of the data base (DB) 35 connected to the computer (server) 34 are appropriately copied (uploaded) on the side of the computer terminal (client) 27 and sent out to a printer not shown or the like.
The above-described conventional network linkage type PBX system, however, has the following problems.
More specifically, in a conventional network linkage type PBX system, the PBXs 11, 21 and 31 and the computers (servers) 14, 24 and 34 are one-to-one connected to each other. When failures occur in the computers (server) 14 and 34, therefore, for the PBXs 11 and 31 and a remote computer terminal to inter-work, it is necessary to provide the base 20 with the computer terminals (clients) 26 and 27 for subsidiary work and also with the dedicated lines L3 and L4 to be disposed without the need of the PBX 21, which makes facility complicated.